Presently, so called Hot Spots are becoming increasingly popular among users of devices capable of wirelessly connecting to such Hot Spots. The devices may be computers, laptops, Personal Digital Assistants (PDAs), cellular phones and the like. The Hot Spots allow the devices to wirelessly access numerous services, such as internet access, printer services and file storage services.
A Wireless Local Area Network access point (WLAN access point) is a known manner of providing a Hot Spot. A user that desires to access a service provided via the Hot Spot is often required to enter an encryption key to gain access. The encryption key may be provided free of charge or in exchange of a fee. As an example, a guest brings a device capable of communicating with the WLAN access point to a home of a host. Next, the guest wishes to use a printer, connected to a WLAN access point in the home of the host. Then, the guest enters an encryption key, received by the host, into the device. Thereby, the guest is allowed to access the WLAN access point and the printer connected thereto. Availability of the WLAN access point, i.e. how access to the WLAN access point is managed, is handled by the encryption key (or in some cases even without the encryption key).
Providers of telecommunication networks have realized the potential of Hot Spots. Therefore amongst other reasons, so called femto base stations are being developed in order to compete with the WLAN access point and the like. Femto base stations are developed as a part of Third Generation Partnership Project (3GPP) for both Universal Mobile Telecommunications System (UMTS) and Long Term Evolution (LTE).
A femto base station manages a number of cells. The femto base station broadcasts at least one PLMN (Public Land Mobile Network) identity in the cells. The PLMN identity, broadcast in the cells, belongs to an operator of the femto base station. A subscription is associated with an operator and, hence, also a PLMN identity which belongs to the operator. The PLMN identity is stored on a Subscriber Identity Module card (SIM card), or a Universal Subscriber Identity Module card (USIM card). The SIM card can be put inside a user equipment (UE), such as a mobile phone or the like. When the user equipment has a subscription, it can be said to belong to one of the following three categories in respect of the femto base station:                A first category, if the PLMN identity of the subscription matches the PLMN identity broadcast in the cell. The PLMN(s) broadcast in the cells are often referred to as Home PLMN (HPLMN) of the femto base station.        A second category, if the PLMN identity of the user equipment, i.e. of the subscription, is different from the HPLMN of the femto base station. In this case, the PLMN identity of the user equipment is often referred to as a Visitor PLMN (VPLMN) identity. If it is assumed that the HPLMN identity belongs to a first operator and the VPLMN identity belongs to a second operator, the second category can be divided into the following two sub-categories:                    A first sub-category, if the second operator that owns the VPLMN identity has a roaming agreement with the first operator that owns the HPLMN identity. In short, a roaming agreement enables a user equipment to connect to other PLMN identities than the HPLMN identity.            A second sub-category, if the second operator does not have a roaming agreement with the first operator. When there is no roaming agreement between the first and second operators, a network of the first operator (HPLMN) and a network of the second operator (VPLMN) are called non-cooperating networks.                        
A user equipment, belonging to the second operator with the VPLMN identity, which has no roaming agreement with the first operator with the HPLMN identity, is not allowed to access the femto base station broadcasting the HPLMN identity. The business rationale is that the added traffic load, generated by such user equipment, implies added costs without at the same time rendering incomes to the first operator with the HPLMN identity.
In an existing system comprising a femto base station, it is assumed that the femto base station is connected to a core network, i.e. roaming visitors use standard non-access stratum signalling (NAS signalling) to attach to the network. After the user equipment has access to the femto base station, i.e. when a visiting user equipment is attached to the PLMN, it can use either global services via the core network, or local services.
Returning to the example with the guest above, it is now assumed that the host manages a local area network (LAN) comprising a femto base station as replacement of the WLAN access point. Moreover, it shall be assumed that the guest, i.e. the device of the guest, does not belong to the HPLMN identity of the femto base station and that there is no roaming agreement between the HPLMN identity of the femto base station and the VPLMN identity of the guest. This means that a first SIM card, installed into the device of the guest, does not belong to the HPLMN identify of the femto base station. In such case, the visitor will have to put in a second SIM card into the device. The second SIM card, belonging to the HPLMN identity of the femto base station, may be provided by the host. Now, it will be possible for the device of the guest to access the femto base station. Disadvantageously, manual interaction is required. In addition, the device may even have to be restarted, while causing interruptions, such as dropped IP connection, in order to access a service provided by the femto base station.
In order to improve availability of femto base stations, it has been made possible to associate a femto base station with multiple PLMN identities. In this manner, it is intended that the visitor can find one PLMN identity of the femto base station that is compatible with the PLMN identity of the visitor's device. It is currently possible for a femto base station to broadcast up to 6 PLMN identities. In order for a femto base station to broadcast PLMN identities associated to different operators, business agreements, such as roaming agreements or other business agreement for a purpose of determining how to share costs and/or revenues when UEs are served as guests (or visitors) in a network, need to be reached. This may be viable if femto base stations are allocated to a carrier that is not used by macro cells operating in the same area as the femto base station. Operators could then split costs for the spectrum license of the used carrier. However, it may be difficult to agree on proportions of the costs. Moreover, in some cases it may be that a carrier, not used by the macro cells, is not available.
Moreover, in another scenario, a femto base station belongs to one PLMN identity. The PLMN identity can be reconfigured to match a preference of a visitor. In this manner, devices (of visitors) belonging to only one PLMN identity can be supported simultaneously. Furthermore, interruption and/or delay in conjunction with reconfiguration may be considerable.
In yet another scenario, where the device of the visitor belongs to the PLMN identity of the femto base station, the device may still be prevented from accessing the femto base station because of a so called allowed Closed Subscriber Group (CSG) List. The device will be blocked from accessing the femto base station if the CSG identifier (or identity) of the femto base station is not found in the allowed CSG List (specific for this UE). After manually adding the device to the allowed CSG List, the device may access the femto base station. Administration of adding the device to the allowed CSG List may be cumbersome.
Hence, there is a need for an improvement of the availability of the femto base station.